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  1. #1
    mdehghani is offline Member
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    Jan 2017
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    Default String Json to Map?

    hi everyone!
    i'm trying to convert a string json read from remote url (including integers and doubles) to Map using the Gson library but It appears that i always receieve a null.
    the string jason is :

    [{"Month":136901,"CPI":2.4},{"Month":136902,"CPI":2 .4}]

    and my code is:

    String json = jsonString; //mentioned above
    Gson gson = new Gson();
    Map<Integer, Double> map = new HashMap<Integer, Double>();
    map = (Map<Integer, Double>)gson.fromJson(json, map.getClass());
    Last edited by mdehghani; 01-10-2017 at 09:08 PM.

  2. #2
    jim829 is offline Senior Member
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    Default Re: String Json to Map?

    I am not familiar with the json library API but it looks to me like the map should be Map<String, Double>. Nor do I understand how the library constructs the map since Month and CPI occur twice but a Map must have unique keys for all values.

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  3. #3
    jameswarner is offline Member
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    Default Re: String Json to Map?

    You can convert JSON string to java map object using Jackson's data binding. If you need example please check reference code link How to convert JSON string to Map? - Jackson JSON examples

  4. #4
    JosAH's Avatar
    JosAH is offline Moderator
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    Default Re: String Json to Map?

    The outer JSON object is an array [ ... ] and it contains two objects { ... }' the outer object cannot be converted to a HashMap (or whatever Map).

    kind regards,

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  5. #5
    gozzy is offline Member
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    Default Re: String Json to Map?

    Looks like you'd be better of with an array or List of some object that models the json

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